The present invention pertains to rope braiding apparatus and methodology, and in particular pertains to automated manufacture of commercial grade rope and sheathing having a square shaped cross section.
Square rope made by hand has been known and used since the 15th century. Despite numerous advantages in special applications, such rope has not been commercially available due to the expense of its manufacture, lack of uniform high quality tight braid, and practical limits on the length of rope when braided by hand. The hand braiding exhibits uneven, loose braids which decrease strength, contribute to rapid wear and in general detract from the usefulness and commercial acceptability.
One of the significant advantages of such rope is in the secure hand-to-rope grip provided by the square shape which tends to better fit the human hand. Thus applications in which ropes are handled can use this product to advantage. Safety lines, marine mooring lines, and mountaineering rope in particular provide good examples of important uses of this type of rope. Other applications include hoisting or other similar situations in which one end of the rope is free to rotate and excessive twisting may occur. The square shaped configuration resists twisting and causes the rope to return to a neutral untwisted state. The braided rope may be formed as a sheath and used to cover guy wire, conduit, hose or other similar article that needs to be gripped securely. Other advantages and special applications are noted below.
In the prior art of hand braiding square rope, it is necessary to first provide a plurality of cut strands which are then laid out lengthwise and worked into the braiding point by hand. The difficulty of working with the numerous strands, a minimum of eight separate strands are required, limits the practical length of the resulting rope to about thirty feet. An attempt to hand braid ropes of greater length results in the impossible task of managing the constituent strands. Furthermore, such hand braided rope does not, as a practical matter, accommodate a center strand or other center core, such as a hose. The nature of the square shaped braiding process results in a rope that will tend to stretch more than other types of braided rope and hence the center strand, if it can be incorporated into the rope, serves to greatly resist such stretching and produce a more usable and practical rope product. In other applications where a hollow rope braid is desired, as in the case of sheathing mentioned above, hand braiding closes on the center, making it unsuitable as a sheath.
Another rope forming process which is related, but should not be confused with the hand braided square rope process, is known as the crown knot. A series of such knots are formed from a set of four rope strands. The resulting product does have a generally square shaped exterior. However, the configuration of the knot forming process is entirely different from a braided rope that is the subject matter of this invention and does not have the advantages and capabilities of a true square braided rope.